本文關(guān)鍵詞：延遲容忍網(wǎng)絡中路由算法的研究　出處：《電子科技大學》2015年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 延遲容忍網(wǎng)絡 路由算法 條件接觸間隔時間 接觸持續(xù)時間

【摘要】：隨著科技的進步,具有無線接口的通信設備越來越普及。在這個過程中出現(xiàn)一種特殊的無線移動網(wǎng)絡——延遲容忍網(wǎng)絡(Delay Tolerant Network,DTN)。與傳統(tǒng)的無線網(wǎng)絡不同,DTN不存在持續(xù)的網(wǎng)絡連接并具有節(jié)點頻繁移動、資源受限等特點。由于DTN的這些特性,DTN的路由變得非常具有挑戰(zhàn)性,因為它必須處理網(wǎng)絡中存在的網(wǎng)絡劃分、長延時和節(jié)點動態(tài)拓撲等問題。DTN最初被用于星際網(wǎng)絡,目前存在多種不同的應用場景,包括無線傳感器網(wǎng)絡、軍事自組織網(wǎng)絡、車載網(wǎng)絡和社交網(wǎng)絡等等。在DTN中,不可能存在從源端到目的端的持續(xù)網(wǎng)絡連接。因此,在DTN中,消息的傳輸依賴機會路由,其中節(jié)點使用存儲-攜帶-轉(zhuǎn)發(fā)的模式來進行消息路由。然而,基于有限的歷史接觸信息來制定有效的轉(zhuǎn)發(fā)策略仍然是具有挑戰(zhàn)性的。本文首先研究了DTN中已存在的一種依據(jù)歷史相遇和傳輸信息的概率路由算法(Probabilistic Routing Protocol using History of Encounters and Transitivity,Prophet)。然后引入了一種附加測度——條件接觸間隔時間,這一測度只使用本地的歷史相遇信息來計算兩個節(jié)點相對于第三個節(jié)點的相遇之間的平均接觸間隔時間。我們還分析了引入的附加測度并說明了它在路由中的重要性。接著引入接觸持續(xù)時間的概念,并分析其合理性。最后本文利用接觸持續(xù)時間和條件接觸間隔時間分別對Prophet的概率計算和轉(zhuǎn)發(fā)策略進行了改進。實驗結(jié)果表明,改進后的Prophet有效地降低了延時,提高了消息的投遞率,減少了網(wǎng)絡開銷。然后在改進后的Prophet基礎上,分析了散發(fā)與等待(Spray and Wait,SW)路由算法在散發(fā)階段和等待階段的不足,提出了一種改進的基于概率的散發(fā)與等待路由算法。在原有的散發(fā)與等待路由算法的散發(fā)階段中,節(jié)點盲目地將消息副本散發(fā)給所有與它相遇的節(jié)點。基于這一點,本文對散發(fā)與等待路由算法的散發(fā)策略進行改進�？紤]節(jié)點的所有鄰居節(jié)點的消息遞交概率值,應用公式計算出散發(fā)給各節(jié)點的消息副本數(shù)。另外在等待階段,攜帶消息副本的節(jié)點不再是等待目的節(jié)點然后直接交付。當節(jié)點在移動的過程中遇到與目的節(jié)點相遇概率更大且條件接觸間隔時間更小的節(jié)點的時候,將消息副本將轉(zhuǎn)發(fā)給該節(jié)點。仿真結(jié)果表明,改進后的路由算法在消息的遞交成功率、平均端到端時延、網(wǎng)絡開銷等方面有良好的性能。
[Abstract]:With the progress of science and technology, the communication equipment with wireless interface is becoming more and more popular. In this process, there is a special wireless mobile network, the Delay Tolerant Network (DTN). Unlike traditional wireless networks, DTN does not have a continuous network connection and has the characteristics of frequent mobile nodes and limited resources. Because of these characteristics of DTN, routing of DTN is very challenging, because it must deal with network partition, long delay and node dynamic topology. DTN was originally applied to interplanetary network. There are many different application scenarios at present, including wireless sensor network, military self organizing network, vehicular network and social network. In DTN, it is not possible to have a continuous network connection from the source to the destination. Therefore, in DTN, the transmission of messages depends on the opportunity routing, where the nodes use the storage - carry - forward mode for message routing. However, it is still challenging to make effective forwarding strategies based on limited historical contact information. In this paper, we first study a Probabilistic Routing Protocol using History of Encounters and Transitivity, which exists in DTN, which is based on historical encounter and transmission information. Then an additional measure -- the conditional contact interval time is introduced. The measure only uses the local historical encounter information to calculate the average contact interval between two nodes relative to the third nodes. We also analyzed the additional measure introduced and explained its importance in routing. Then the concept of contact duration is introduced and its rationality is analyzed. At last, the probability calculation and forwarding strategy of Prophet are improved by using contact duration and conditional contact interval time respectively. The experimental results show that the improved Prophet effectively reduces the delay, improves the delivery rate of the message, and reduces the network overhead. Then, on the basis of the improved Prophet, we analyze the shortcomings of the Spray and Wait (SW) routing algorithm in the sporadic stage and the waiting stage, and propose an improved probabilistic based distributed and wait routing algorithm. In the emanating phase of the original emission and waiting routing algorithm, nodes blindly distribute the copy of the message to all the nodes that meet it. Based on this, this paper improves the emission strategy of the emission and waiting routing algorithms. The number of messages sent to each node is calculated by using the application formula to calculate the probability value of the message submitted by all the neighbor nodes of the node. In addition, in the waiting phase, the nodes that carry a copy of the message are no longer waiting for the destination node and then delivering it directly. When nodes move in the process of encountering nodes that have greater probability of meeting with the destination node and smaller conditional contact intervals, the message copy will be forwarded to the node. The simulation results show that the improved routing algorithm has good performance in the success rate of message delivery, the average end to end delay, the network overhead and so on.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN929.5
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本文編號：1340048